Enhancement of secondary metabolite production in callus cultures of glycyrrhiza glabra linn through elicitation

Abstract

Glycyrrhiza glabra Linn. (Licorice) is a medicinal plant of family Fabaceae which possesses a wide range of phytochemicals and is well known for its pharmaceutical properties mainly attributed to the presence of flavonoids. Major flavonoids of Glycyrrhiza glabra such as licochalcone A, liquirtigenin and licochalcone B possess distinguished medicinal properties like anti-inflammatory, antioxidant, antitumor, antiviral and antimicrobial activities which complement the age long medicinal uses of licorice extracts. Wide occurrence, complex diversity and potential benefits of such flavonoids on human health have made it one of the well-studied group of phytochemicals. However, most of the studies on licochalcone A, liquirtigenin, and licoisoflavone B are confined to their pharmacological properties. The chemical synthesis of most of these flavonoids is not feasible due to the complex structure and chirality exhibited by these compounds and the in vivo production is often not consistent due to several environmental factors. However, plant tissue cultures offer a good alternative for consistent production of target flavonoids and elicitation of tissue cultures extend an efficient strategy to increase the production of these metabolites. Therefore, this research is focused on the enhancement of production of three major flavonoids - licochalcone A, liquirtigenin and licoisoflavone B, in Glycyrrhiza glabra callus cultures using various elicitors. Callus cultures of Glycyrrhiza glabra were established and maintained using nutrient media supplemented with growth hormones in various concentrations and combinations. Elicitation of callus cultures was done using different concentrations of biotic elicitors (chitosan and yeast extract), abiotic elicitors (jasmonic acid and salicylic acid) and precursors of phenylpropanoid pathway (phenylalanine and cinnamic acid). The elicited cultures were evaluated quantitatively and qualitatively for enhanced production of licochalcone A, liquirtigenin and licoisoflavone B and the mechanisms